"Debugging and troubleshooting", "List of MyChat Client errors", "Error #0313".
 
Error

Error #0313: the client's version (XX) is not compatible with the server's version (YY). Please, update MyChat Client manually or install it to a user's profile
 

Error description

During connection to the server, it turned out, that MyChat Client  version is not compatible with the server's version (they must match). Update  MyChat Client.

 
Problem solution

Your MyChat Client installed to Program Files and can't update automatically from your  server. You need elevated privileges. Update it manually (do it each time during next updates), or install it to the Windows user's profile(standard installation).

 

It is better to do via "Apps and features": delete MyChat Client (without deleting a profile with data), and then install MyChat Client to a user's profile.